Levulinic acid is a well-known product of hexose acid hydrolysis, and can be inexpensively obtained from cellulose feedstocks. Consequently, it is an attractive starting material in producing many useful 5-carbon compounds and their derivatives. For example, N-cyclohexyl-2-pyrrolidone is used as a solvent or intermediate in many industrial applications, including the electronics industry (photo-resist stripping solutions), industrial cleaners, oil/gas well maintenance, and fiber dyeing.
U.S. Pat. No. 3,337,585 discloses a process for preparing 5-methyl-1-alkyl-2-pyrrolidone utilizing levulinic acid and a primary alkyl amine at a temperature of 50° C. to 350° C. under carbon monoxide at a pressure of 1.0 to 101 MPa. Additional potential primary amines include alkylene diamines, aryl amines and cycloalkyl amines. In U.S. Pat. No. 3,235,562 a vapor phase process is used for the production of lactams by reductive amination of oxo carboxylic acid compounds. Alkyl or aryl volatile primary amines may be used. Candeloro and Bowie (Aust. J. Chem., 1978, 31:2031-2037) describe a process for producing 5-methyl-2,3-dihydro-1-H-benzazepin-2-one and 5-(2-methyl-5-oxo-1-phenylpyrrolidin-2-yl) 4-oxo-N-phenylpentanamide by reacting levulinic acid with aniline under a nitrogen atmosphere.
An efficient and low cost process for the production of aryl, alkyl and cycloalkyl pyrrolidones would be advantageous.